Upgrade libsrt to v1.5.3. v5.0.183 (#3808)

trunk/3rdparty/srt-1-fit/scripts/CheckCXXAtomic.cmake

@@ -0,0 +1,62 @@
+#
+# SRT - Secure, Reliable, Transport
+# Copyright (c) 2021 Haivision Systems Inc.
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+#
+
+# Check for c++11 std::atomic.
+#
+# Sets:
+#     HAVE_CXX_ATOMIC
+#     HAVE_CXX_ATOMIC_STATIC
+
+include(CheckCXXSourceCompiles)
+include(CheckLibraryExists)
+
+function(CheckCXXAtomic)
+
+   unset(HAVE_CXX_ATOMIC CACHE)
+   unset(HAVE_CXX_ATOMIC_STATIC CACHE)
+
+   unset(CMAKE_REQUIRED_FLAGS)
+   unset(CMAKE_REQUIRED_LIBRARIES)
+   unset(CMAKE_REQUIRED_LINK_OPTIONS)
+
+   set(CheckCXXAtomic_CODE
+      "
+      #include<cstdint>
+      #include<atomic>
+      int main(void)
+      {
+         std::atomic<std::ptrdiff_t> x(0);
+         std::atomic<std::intmax_t> y(0);
+         return x + y;
+      }
+      ")
+
+   set(CMAKE_REQUIRED_FLAGS "-std=c++11")
+
+   check_cxx_source_compiles(
+      "${CheckCXXAtomic_CODE}"
+      HAVE_CXX_ATOMIC)
+
+   if(HAVE_CXX_ATOMIC)
+      # CMAKE_REQUIRED_LINK_OPTIONS was introduced in CMake 3.14.
+      if(CMAKE_VERSION VERSION_LESS "3.14")
+         set(CMAKE_REQUIRED_LINK_OPTIONS "-static")
+      else()
+         set(CMAKE_REQUIRED_FLAGS "-std=c++11 -static")
+      endif()
+      check_cxx_source_compiles(
+         "${CheckCXXAtomic_CODE}"
+         HAVE_CXX_ATOMIC_STATIC)
+   endif()
+
+   unset(CMAKE_REQUIRED_FLAGS)
+   unset(CMAKE_REQUIRED_LIBRARIES)
+   unset(CMAKE_REQUIRED_LINK_OPTIONS)
+
+endfunction(CheckCXXAtomic)